| RefNo | Title | Date |
| EC/1893/05 | Ewart, James Cossar: certificate of election to the Royal Society | |
| EC/1893/06 | Ewart, James Cossar: certificate of election to the Royal Society | |
| MM/15/8 | Letter from GJ Romanes to George Gabriel Stokes | 20 June 1881 |
| IM/Maull/001338 | Ewart, James Cossar | nd |
| NLB/2/666 | Copy letter from an unknown correspondent, to the Cambridge Scientific Instrument Company | 6 October 1888 |
| NLB/41/17 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 24 September 1909 |
| NLB/2/347 | Copy letter from Herbert Rix, to Professor James Cossar Ewart, University of Edinburgh | 7 May 1888 |
| NLB/2/407 | Copy letter from Herbert Rix, to John Newport Langley, Fellow of the Royal Society | 4 June 1888 |
| NLB/2/413 | Copy letter from Herbert Rix, to John Newport Langley, Fellow of the Royal Society | 7 June 1888 |
| NLB/2/466 | Copy letter from Herbert Rix, to Lord Rayleigh [John William Strutt, Royal Society] | 10 July 1888 |
| NLB/2/599 | Copy letter from an unknown correspondent, to the Cambridge Scientific Instrument Company | 25 September 1888 |
| NLB/2/796 | Copy letter from Herbert Rix, to Professor James Cossar Ewart, [Fellow of the Royal Society] | 7 November 1888 |
| NLB/2/1010 | Copy letter from Herbert Rix, to Professor James Cossar Ewart | 29 January 1889 |
| NLB/2/896 | Copy letter from Herbert Rix, to Professor James Cossar Ewart, Edinburgh | 10 December 1888 |
| NLB/2/499 | Copy letter from Herbert Rix, to Professor Michael Foster, Secretary, Royal Society | 20 July 1888 |
| NLB/3/153 | Copy letter from an unknown correspondent, to Mr Collings, 172 Strand | 29 March 1889 |
| NLB/7/71 | Copy letter from Herbert Rix, to Professor James Cossar Ewart, 2 Belford Park, Edinburgh | 22 November 1892 |
| NLB/6/795 | Copy letter from Herbert Rix, to the Cambridge Engraving Company | 14 July 1892 |
| NLB/7/708 | Copy letter from Herbert Rix, to Mr Collings, 172 Strand | 12 April 1893 |
| NLB/8/839 | Copy letter from Herbert Rix, to W Lawton, Marland Villa, Torrington, Devon | 8 January 1894 |
| RR/17/97 | Referee's report by James Cossar Ewart, on a paper 'Studies on the development of larval nephridia. Part II.—Polygordius' by Cresswell Shearer | [October 1906] |
| NLB/20/8 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 12 January 1900 |
| NLB/20/671 | Copy letter from an unknown correspondent, to Professor James Cossar Ewart, Fellow of the Royal Society | 14 June 1900 |
| NLB/20/804 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, The Bungalow, Penicuik, Midlothian | 12 July 1900 |
| NLB/22/742 | Copy letter from Robert William Frederick Harrison, to Professor [James Cossar] Ewart, Fellow of the Royal Society | 10 July 1901 |
| NLB/32/76 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 21 December 1905 |
| NLB/35/496 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 5 June 1907 |
| NLB/41/584 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 18 January 1910 |
| NLB/39/232 | Copy letter from Robert William Frederick Harrison to Professor J [James] C [Cossar] Ewart, Fellow of the Royal Society | 14 December 1908 |
| NLB/40/238 | Copy letter from Robert William Frederick Harrison to Messrs Harrison & Sons, St Martin's Lane, WC | 5 May 1909 |
| NLB/38/486 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 12 August 1908 |
| NLB/40/392 | Copy letter from Robert William Frederick Harrison to Professor J [James] C [Cossar] Ewart FRS | 3 June 1909 |
| NLB/40/499 | Copy letter from Robert William Frederick Harrison to Professor J [James] C [Cossar] Ewart FRS | 16 June 1909 |
| NLB/40/689 | Copy letter from Robert William Frederick Harrison to Professor J [James] C [Cossar] Ewart FRS | 19 July 1909 |
| NLB/41/474 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 21 December 1909 |
| RR/8/288 | Referee's report by Michael Foster, on the Croonian Lecture 'Observations on the locomotor system of Echinodermata' by George John Romanes and James Cossar Ewart | 22 May 1881 |
| RR/17/399 | Referee's report by Charles William Andrews, on a paper 'The possible ancestors of the horses living under domestication' by James Cossar Ewart | June 1909 |
| RR/14/226 | Referee's report by James Cossar Ewart, on a paper 'On the formation of the pelvic plexus, with especial reference to the nervus collector in the genus Mustelus' by Reginald Crundall Punnett | nd [January 1900] |
| RR/15/49 | Letter from Louis Compton Miall, on a paper 'Variation' by James Cossar Ewart to William Abbott Herdman | 5 May 1900 |
| NLB/65/827 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Professor [James Cossar] Ewart, FRS | 15 January 1924 |
| RR/10/144 | Referee's report by John Newport Langley, on a paper 'On the development of the electric organ of Raia batis' by James Cossar Ewart | 24 April 1888 |
| NLB/70/859 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Professor [James Cossar] Ewart, FRS | 20 October 1927 |
| NLB/72/252 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Professor [James Cossar] Ewart, FRS | 8 June 1929 |
| NLB/2/886 | Copy letter from Herbert Rix, to Professor James Cossar Ewart | 7 December 1888 |
| NLB/2/405 | Copy letter from Herbert Rix, to Professor Michael Foster [Royal Society] | 1 June 1888 |
| NLB/12/739 | Copy letter from Herbert Rix, to the Direct Photo-Engraving Company, 9 Barnsbury Park, N. | 11 April 1896 |
| NLB/33/639 | Copy letter from Robert William Frederick Harrison, to Professor James Cossar Ewart, Fellow of the Royal Society | 13 October 1906 |
| NLB/40/632 | Copy letter from Robert William Frederick Harrison to Professor J [James] C [Cossar] Ewart FRS | 10 July 1909 |
| RR/17/400 | Referee's report by Richard Lydekker, on a paper 'The possible ancestors of the horses living under domestication' by James Cossar Ewart | 3 June 1909 |
| NLB/22/719 | Copy letter Sir Michael Foster, to Professor [James Cossar] Ewart, [Fellow of the Royal Society] | 4 July 1901 |
| PP/4/40 | Paper, 'On the natural and artificial fertilisation of herring ova' by J [James] Cossar Ewart | 1884 |
| PP/15/23 | Paper, 'The cranial nerves of the torpedo. Preliminary note' by J C [James Cossar] Ewart | 1890 |
| PP/13/33 | Paper, 'On the cranial nerves of Elasmobranch fishes - preliminary communication' by J [James] Cossar Ewart | 1889 |
| PP/15/22 | Paper, 'On the development of the ciliary or motor oculi ganglion' by J [James] Cossar Ewart | 1890 |
| PP/10/55 | Paper, 'On rigor mortis in fish, and its relation to putrefaction' by J [James Cossar] Ewart | 1887 |
| PP/21/10/1 | Manuscript, 'The electric organ of the skate: Note on an electric centre in the spinal cord' by J [James] Cossar Ewart | 1893 |
| PP/21/10 | Paper, 'The electric organ of the skate: Note on an electric centre in the spinal cord' by J [James] Cossar Ewart | 1893 |
| PP/21/10/2 | Figures, motor cells by J [James] Cossar Ewart | 1893 |
| RR/10/145 | Letter from James Cossar Ewart, to Michael Foster, regarding three papers 'On the development of the electric organ of Raia batis', 'The electric organ of the skate. - On the structure of the electric organ of Raia circularis' and 'The electric organ of the skate.—The electric organ of Raia radiata' by James Cossar Ewart | 5 June 1888 |
| RR/10/146 | Referee's report by John Newport Langley, on two papers 'The electric organ of the skate. - On the structure of the electric organ of Raia circularis' and 'The electric organ of the skate.—The electric organ of Raia radiata' by James Cossar Ewart | 6 June 1888 |
| RR/10/148 | Referee's report by John Newport Langley, on a paper 'The electric organ of the skate.—The electric organ of Raia radiata' by James Cossar Ewart | 9 July 1888 |
| RR/10/149 | Letter from Michael Foster, to John William Strutt, 3rd Baron Rayleigh, regarding a paper 'The electric organ of the skate.—The electric organ of Raia radiata' by James Cossar Ewart | [1888] |
| RR/11/147 | Referee's report by John Newport Langley, on a paper 'The electric organ of the skate.–Observations on the structure, relations, progressive development, and growth, of the electric organ of the skate' by James Cossar Ewart | 30 March 1892 |
| RR/11/148 | Referee's report by Edward Albert Sharpey-Schafer, on a paper 'The electric organ of the skate.–Observations on the structure, relations, progressive development, and growth, of the electric organ of the skate' by James Cossar Ewart | 6 April 1892 |
| RR/15/48 | Referee's report by Louis Compton Miall, on a paper 'Variation' by James Cossar Ewart | 26 March 1900 |
| RR/15/50 | Referee's report by Walter Frank Raphael Weldon, on a paper 'Variation' by James Cossar Ewart | 29 April 1900 |
| RR/21/6 | Referee's report by James Cossar Ewart, on a paper 'A description of the skull and skeleton of a peculiarly modified rupicaprine antelope (Myotragus balearicus, Bate), with a notice of a new variety, M. balearicus var. major' by Charles William Andrews | [September 1914] |
| RR/10/147 | Referee's report by Edward Albert Sharpey-Schafer, on two papers 'The electric organ of the skate. - On the structure of the electric organ of Raia circularis' and 'The electric organ of the skate.—The electric organ of Raia radiata' by James Cossar Ewart | 20 June 1888 |
| NLB/38/542 | Copy letter from Joseph Larmor and Sir Archibald Geikie, to Henry Frederick Baker, Fellow of the Royal Society, and others | 16 September 1908 |
| MC/17 | Volume 17 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1897-1899 |